1. Field of the Invention
The invention is related to the field of tripod constant velocity universal joints and in particular to a tripod constant velocity joint in which the roller is pivotable and radially displaceable relative to the trunnion on which it is mounted.
2. Description of the Prior Art
Tripod constant velocity universal joints such as taught by Devard et al, in U.S. Pat. No. 3,613,396 or Orain in, U.S. Pat. No. 3,757,534, have an inner joint member and an outer joint member. Conventionally, the inner joint member has three radially extending trunnions equally spaced about the inner joint member's axis of rotation. A roller is journaled on each of the trunnions which engage a pair of parallel guideways or tracks provided in the outer joint member. In the early development of these universal joints, the trunnions were cylindrical and the rollers were journaled to the trunnions using roller or pin bearings disposed between the trunnion and the roller. Resilient means were normally provided for movement of the roller relative to the trunnion when the inner joint member was angularly disposed with respect to the outer joint member. In these constant velocity or universal joints, the plane of the roller generally remains parallel to the axis of rotation of the inner joint member. Therefore, when the inner joint member is at an angle to the outer joint member, the roller is at an angle to the guideway causing a compound motion of the roller along the guideway. Part of this motion was a sliding motion of the roller in the guideway which caused the joint to shudder and decrease the efficiency of the universal joint. In some of these universal joints, the guideways were made flat. This solution solved some problems but created new ones.
Wahlmark, in U.S. Pat. No. 3,818,721, provided a first solution to this problem through the use of trunnion members utilizing a multiple component roller in which the mating surfaces of at least two of the roller components mate in drive channels so that the outer roller member could pivot relative to the axis of the trunnion. Therefore, the roller could remain parallel to the guideways even when the inner joint member was angularly disposed relative to the outer joint member. Wahlmark teaches the use of a multiple component roller bearing between an inner roller member and an outer roller member.
In contrast to the teachings of Wahlmark, Orain, in U.S. Pat. No. 4,472,156, teaches the use of diabolo-shaped bearings between the spherically shaped trunnion and a convex shaped inner surface of the roller. Alternatively, Peterson, in U.S. Pat. No. 4,505,688, teaches the use of laminated elastomeric bearings at the interface of the mating spherical surfaces of a multiple component roller.
Otsuka et al, in U.S. Pat. No. 4,379,706, in a first embodiment, teach the use of a roller bearing disposed in an inner annular cavity of the roller which engages a trunnion having a spherical head. In an alternate embodiment, Otsuka et al teach a multiple component roller having three annular members. The inner annular member is slidably received on a cylindrically shaped trunnion and is free to move in an axial direction relative to the trunnion. An intermediate member has a concave spherical inner surface which mates with the external spherical surface of the inner member. The outer member of the roller has a contoured external surface which mates with the contoured surface of the parallel guideways provided in the outer joint member. The inner face between the outer and intermediate members of the multiple component roller have mating annular recesses which are disposed in a plurality of roller bearings. The axial displacement of the multiple component roller relative to the trunnion is provided by the sliding of the inner member of the roller bearing on the cylindrical surface of the trunnion as taught by Drevard et al, Orain, and Peterson as discussed above.
A multiple component roller is taught by Orain, in U.S. Pat. No. 4,472,156, which is comparable to that taught by Otsuka et al except that it is mounted on a spherically shaped trunnion and no provisions are made for radial displacement of the roller relative to the trunnion.